# Cross-Linking Poly(lactic acid) Film Surface by Neutral Hyperthermal Hydrogen Molecule Bombardment.
> 中性超熱水素分子照射によるポリ乳酸フィルム表面の架橋処理


## Abstract

A hyperthermal hydrogen-induced cross-linking (HHIC) technique was developed to improve the water resistance of poly(lactic acid) (PLA) films. Unlike conventional plasma methods, which cause surface damage through uncontrolled charged-particle bombardment, HHIC generates energy-controlled neutral hydrogen molecules that selectively sever C-H bonds on the PLA surface without disrupting backbone C-C bonds. The resulting carbon radicals undergo recombination, forming a dense cross-linked barrier layer. This layer substantially enhances both hydrophobicity and water vapor barrier performance of the PLA film. Importantly, the original mechanical strength and optical transmittance of the films are preserved, demonstrating the selectivity advantage of the HHIC approach for surface modification of biodegradable polymer films.

### Mechanism

Energy-controlled neutral hyperthermal hydrogen molecules selectively cleave C-H bonds on the PLA surface; the resulting carbon radicals recombine to form a dense cross-linked layer that acts as a water vapor barrier.

## Bibliographic

- **Authors**: Du W, Shao H, He Z, Tang C, Liu Y, Shen T, et al.
- **Journal**: J Agric Food Chem
- **Year**: 2015 (2015-12-16)
- **PMID**: [26594874](https://pubmed.ncbi.nlm.nih.gov/26594874/)
- **DOI**: [10.1021/acs.jafc.5b04249](https://doi.org/10.1021/acs.jafc.5b04249)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: positive

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 26594874. https://h2-papers.org/en/papers/26594874
> **Source**: PubMed PMID [26594874](https://pubmed.ncbi.nlm.nih.gov/26594874/)